Detection of NH3 Molecules in the Interstellar Medium by Their Microwave Emission

A. C. Cheung, D. M. Rank, C. H. Townes, D. D. Thornton, and W. J. Welch
Phys. Rev. Lett. 21, 1701 – Published 16 December 1968
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Abstract

Ammonia has been found in the direction of the galactic center by detection of its J=1, K=1 inversion transition. The region of emission closely corresponds to the position, velocity, and size of strong OH absorption. Collisional and radiative excitation mechanisms are discussed. The column density of NH3 and the kinetic temperature of the interstellar gas cloud are estimated to be 2×1016/cm2 and 23°K, respectively.

  • Received 15 November 1968

DOI:https://doi.org/10.1103/PhysRevLett.21.1701

©1968 American Physical Society

Authors & Affiliations

A. C. Cheung, D. M. Rank, and C. H. Townes

  • Department of Physics, University of California, Berkeley, California

D. D. Thornton and W. J. Welch

  • Radio Astronomy Laboratory, Space Sciences Laboratory, and Department of Electrical Engineering, University of California, Berkeley, California

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Issue

Vol. 21, Iss. 25 — 16 December 1968

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